Articulated stapling with fire lock

ABSTRACT

A loading unit for a surgical apparatus includes a shaft assembly, an end effector extending from the shaft assembly, an articulation rod, and a fire lock assembly. The articulation rod positioned to articulate the end effector relative to the shaft assembly between an unarticulated position and an articulated position. The fire lock assembly movable in response to movement of the articulation rod. The fire lock assembly configured to selectively prevent the end effector from firing.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/014,000, filed Jun. 21, 2018, the entire contents of which areincorporated by reference herein.

TECHNICAL FIELD

The present disclosure relates to surgical stapling apparatus, devicesand/or systems for performing endoscopic surgical procedures and methodsof use thereof.

BACKGROUND

Surgical stapling apparatus that clamp, cut and/or staple tissue betweenopposing jaw structure are well known in the art. Such surgical staplingapparatus can include loading units with an end effector having twoelongated jaw members used to capture or clamp tissue. One of the twojaw members usually carries a staple cartridge that houses a pluralityof staples while the other of the two jaw members has an anvil forforming the staples as the staples are driven from the staple cartridge.Generally, a stapling operation is effectuated by a cam bar, a drivesled or other similar mechanism having a cam member that travelslongitudinally through channels defined in the staple cartridge and actsupon staple pushers in the channels to sequentially eject the staplesfrom the staple cartridge. Since these stapling apparatus are typicallyutilized during endoscopic or laparoscopic procedures in which surgeryis performed through small incisions or narrow cannulas inserted throughthe small incisions, such stapling operation is often effectuated whenthe end effector is disposed in an articulated position relative to thestapling apparatus to enable the end effector to reach remote surgicalsites within a patient's body.

SUMMARY

Accordingly, the present disclosure is directed to a surgical staplingapparatus for use during laparoscopic and/or endoscopic surgicalprocedures that can be employed to provide firings of the surgicalstapling apparatus while an end effector thereof is disposed in anarticulated position. The surgical stapling apparatus includes a firelock assembly to prevent the surgical stapling apparatus from firingwhen the end effector is not in the articulated position.Advantageously, the fire lock assembly prevents inadvertent firing ofthe surgical stapling apparatus when the end effector is unarticulated(or not articulated to a predetermined angle such as about 90 degrees),but enables clamping and/or unclamping of anvil and cartridge assembliesof the end effector for advancing end effector through small diameterssuch as through a cannula of a surgical access device.

In one aspect of the present disclosure, a loading unit for a surgicalapparatus is provided. The loading unit includes a shaft assembly, anend effector coupled to the shaft assembly, an I-beam assembly supportedin the shaft assembly, and a fire lock assembly supported on the shaftassembly. The end effector is positioned to articulate relative to theshaft assembly between an unarticulated position and an articulatedposition. The I-beam assembly is selectively movable relative to the endeffector to fire the end effector. The fire lock assembly is configuredto prevent the I-beam assembly from firing the end effector when the endeffector is disposed in the unarticulated position.

In some embodiments, the I-beam assembly may include one or more knifebars that support an I-beam configured to advance through the endeffector to fire the end effector. The fire lock assembly may include afire lock that is positioned to engage the one or more knife bars toprevent the I-beam from firing the end effector when the end effector isin the unarticulated position. The fire lock and the one or more knifebars may be disengaged when the end effector is in the articulatedposition such that the I-beam can advance through the end effector forfiring the end effector.

In embodiments, the end effector may include an anvil assembly and acartridge assembly that are pivotally coupled together and movablebetween an unclamped position and a clamped position.

In certain embodiments, the I-beam assembly may be configured toposition the anvil and cartridge assemblies in the clamped position whenthe end effector is disposed in the unarticulated position or thearticulated position.

In some embodiments, the fire lock assembly may include a fire lock anda spring that is positioned to urge the fire lock toward a firstposition. The fire lock may be positioned to prevent the I-beam assemblyfrom advancing through the end effector when in the first position.

The loading unit may further include an articulation rod that is movableto articulate the end effector relative to the shaft assembly. Thearticulation rod may be positioned to move the fire lock to a secondposition as the end effector moves from the unarticulated position tothe articulated position. The I-beam assembly may be positioned toadvance through the end effector to fire the end effector when the firelock is disposed in the second position.

In certain embodiments, the loading unit may further include a pivotguide that may be positioned to curve the I-beam assembly into the endeffector.

According to another aspect of the present disclosure, a surgicalstapling apparatus is provided. The surgical stapling apparatus includesa shaft assembly, an end effector coupled to the shaft assembly, a knifebar, and a fire lock. The end effector is coupled to the shaft assemblyand positioned to articulate relative to the shaft assembly between anunarticulated position and an articulated position. The knife barsupports an I-beam and is selectively movable relative to the shaftassembly. The fire lock is configured to engage the knife bar to preventthe I-beam from advancing through the end effector when the end effectoris disposed in the unarticulated position.

In some embodiments, the end effector may include an anvil assembly anda cartridge assembly that are movable between an unclamped position anda clamped position. The I-beam may be positioned to advance into aproximal end portion of the end effector to move the anvil and cartridgeassemblies from the unclamped position to the clamped position. The firelock may disengage from the knife bar as the end effector moves from theunarticulated position to the articulated position. The fire lock mayprevent the I-beam from advancing distally beyond the proximal endportion of the end effector when the end effector is disposed in theunarticulated position.

In some embodiments, the end effector may be articulated approximately90 degrees relative to a longitudinal axis defined through shaftassembly when the end effector is disposed in the articulated position.

The surgical stapling apparatus may further include an articulation rodsupported by the shaft assembly. The articulation rod may be configuredto articulate the end effector relative to the shaft assembly. Thearticulation rod may define an elongated slot therethrough that may bepositioned to receive the fire lock therein. The fire lock may bepositioned to slide along the elongated slot as the articulation rodmoves the end effector relative to the shaft assembly. The articulationrod may be positioned to engage the fire lock to pivot the fire lockrelative to the knife bar.

In embodiments, the surgical stapling apparatus may further include apivot guide pivotally coupled to a proximal end portion of the endeffector. The pivot guide may be positioned to cause the knife bar tobend around the pivot guide when the end effector is disposed in thearticulated position. The pivot guide may be positioned to limit axialmovement of the knife bar when the end effector is disposed in theunarticulated position.

Other aspects, features, and advantages will be apparent from thedescription, the drawings, and the claims that follow.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the disclosureand, together with a general description of the disclosure given above,and the detailed description of the embodiment(s) given below, serve toexplain the principles of the disclosure, wherein:

FIG. 1 is a perspective view of a surgical stapling apparatus inaccordance with the principles of the present disclosure, the surgicalstapling apparatus including a loading unit with an end effector thereofshown in an unarticulated position;

FIG. 2 is a perspective view of the surgical stapling apparatus of FIG.1 with the end effector thereof shown in an articulated position;

FIG. 3 is an enlarged, perspective view of a distal end portion of thesurgical stapling apparatus of FIG. 1 with the end effector thereofshown in the articulated position;

FIG. 4 is an enlarged, perspective view of the loading unit of thesurgical stapling apparatus of FIG. 1 ;

FIG. 5 is a perspective view of the loading unit of FIG. 4 shown with anouter tube thereof removed for clarity;

FIG. 6 is an enlarged, perspective view, with parts separated, of aninner shaft assembly of the loading unit of FIG. 4 ;

FIG. 7 is an enlarged, perspective view of the indicated area of detaildelineated in FIG. 5 ;

FIG. 8 is an enlarged, perspective view, of a proximal end portion ofthe loading unit as shown in FIG. 5 with portions thereof shown inphantom for clarity;

FIG. 9 is an enlarged, cross-sectional, perspective view of the proximalend portion of the loading unit as illustrated in FIG. 5 and taken alongsection line 9-9 shown in FIG. 7 ;

FIG. 10 is an enlarged, perspective view of the indicated area of detailillustrated in FIG. 6 ;

FIG. 11 is a side, cross-sectional view of the loading unit as takenalong section line 11-11 shown in FIG. 4 , the loading unit illustratedin an unclamped position;

FIG. 12 is an enlarged, cross-sectional, side view of the indicated areaof detail illustrated in FIG. 11 ;

FIG. 13 is a perspective view of the surgical stapling apparatus of FIG.1 shown inserted through an access portal with the loading unit of thesurgical stapling apparatus illustrated in a clamped position;

FIG. 14 is side, cross-sectional view of the loading unit as taken alongsection line 14-14 shown in FIG. 4 , the loading unit shown in theclamped position;

FIG. 15 is an enlarged, cross-sectional, side view of the indicated areaof detail illustrated in FIG. 14 ;

FIG. 16 is an enlarged, perspective view of the loading unit illustratedin FIG. 5 with the end effector thereof shown in the articulatedposition;

FIG. 17 is a top view of FIG. 16 with portions of the loading unit shownin phantom for clarity;

FIG. 18 is an enlarged, perspective view of the indicated area of detailillustrated in FIG. 16 with portions thereof shown in phantom forclarity;

FIG. 19 is side, cross-sectional view of FIG. 18 as taken along sectionline 19-19 shown in FIG. 18

FIG. 20 is an enlarged, perspective view of the distal end portion ofthe surgical stapling apparatus of FIG. 1 with the end effector thereofshown in the articulated position;

FIG. 21 is an enlarged, perspective view of the indicated area of detailillustrated in FIG. 20 with portions thereof removed for clarity;

FIG. 22 is a top, cross-sectional view of FIG. 21 as taken along sectionline 22-22; and

FIG. 23 is a top, cross-sectional view of FIG. 22 with the end effectorshown in the unarticulated position.

DETAILED DESCRIPTION

Embodiments of the presently disclosed surgical stapling apparatus aredescribed in detail with reference to the drawings, in which likereference numerals designate identical or corresponding elements in eachof the several views. As commonly known, the term “clinician” refers toa doctor, a nurse, or any other care provider and may include supportpersonnel. Additionally, the term “proximal” refers to the portion ofstructure that is closer to the clinician and the term “distal” refersto the portion of structure that is farther from the clinician. Inaddition, directional terms such as front, rear, upper, lower, top,bottom, and the like are used simply for convenience of description andare not intended to limit the disclosure attached hereto.

In the following description, well-known functions or constructions arenot described in detail to avoid obscuring the present disclosure inunnecessary detail.

With reference to FIGS. 1-5 , a surgical stapling apparatus 10 of thepresent disclosure includes a housing assembly 12 (which may include oneor more handles that may be manually actuatable to fire surgicalstapling apparatus 10), an adapter assembly 14 secured to housingassembly 12 and extending distally from housing assembly 12, and aloading unit 100 secured to adapter assembly 14 and extending distallyfrom adapter assembly 14. Adapter assembly 14 and loading unit 100define a longitudinal axis “X1-X1” that extends longitudinallytherealong. Loading unit 100 may be disposable and/or include one ormore disposable components.

Loading unit 100 of surgical stapling apparatus 10 is releasably securedto a distal end portion of adapter assembly 14 and includes a shaftassembly 140 and an end effector 110 pivotally coupled to shaft assembly140 about a pivot axis “X2-X2” to enable end effector 110 to move(articulate) between unarticulated (see FIG. 1 ) and articulatedpositions (see FIGS. 2 and 3 ), as indicated by arrows “A.” In thearticulated position, end effector 110 may be disposed at an anglerelative to shaft assembly 140 (see FIG. 3 ). The angle may be anysuitable angle, for example, in certain embodiments, the angle may beabout 90 degrees, plus or minus 15 degrees. End effector 110 includes ananvil assembly 120 and a cartridge assembly 130 that houses a pluralityof staples (not shown) in a reload or cartridge 130 a thereof that maybe selectively replaceable. Cartridge 130 a of cartridge assembly 130may be configured for selective replacement when end effector 110 isarticulated to a predetermined angle, for instance, about 45 degrees.Cartridge assembly 130 is pivotally coupled to anvil assembly 120 aboutpivot axis “X3-X3,” as indicated by arrow “B,” between spaced (e.g.,unclamped; see FIG. 1 ) and approximated (e.g., clamped; see FIG. 16 )positions.

For a more detailed description of similar stapling apparatus, orcomponents thereof, reference can be made, for example, to U.S. Pat. No.8,070,033 to Milliman et al. (“the '033 patent”) and U.S. PatentApplication Publication No. 2016/0242773 to Sadowski et al., the entirecontents of each of which are incorporated herein by reference.

Turning now to FIGS. 4 and 5 , shaft assembly 140 of loading unit 100includes an outer tube 142 and an inner shaft assembly 150 that extendsthrough outer tube 142. Inner shaft assembly 150 includes a proximal endportion 150 a that couples to a distal end portion of adapter assembly14 (see FIG. 1 ) and a distal end portion 150 b that couples to aproximal end portion of end effector 110 of loading unit 100.

With reference to FIGS. 6-10 , inner shaft assembly 150 of shaftassembly 140 includes a lower housing 152 and an upper housing 154 thatsupport and I-beam assembly 156 and an articulation rod 158 therein.Lower housing 152 defines a guide channel 152 a centrally therethroughand a cutout 152 b in a proximal end portion thereof. Upper housing 154defines a guide channel 154 a that is disposed in vertical registrationwith guide channel 152 a of lower housing 152 so that guide channels 152a, 154 a are positioned to slidably receive I-beam assembly 156therethrough. Upper housing 154 defines an insert recess 154 b and alock recess 154 c that is vertically offset from insert recess 154 b anddisposed at an angle relative thereto, for instance, a transverse angle.Upper housing 154 further defines an elongated channel 154 d disposed ina distal portion of insert recess 154 b. I-beam assembly 154 includesknife bars 156 a that support a lockout 156 b on a proximal portionthereof and an I-beam 156 c on a distal end portion of knife bars 156 a.Knife bars 156 a include a lip 156 d on a proximal end portion thereof.For a more detailed description of I-beam assembly 156, or componentsthereof, reference can be made to the '033 patent incorporated byreference above. Articulation rod 158 of inner shaft assembly 150defines an elongated slot 158 a therethrough that is disposed invertical registration with elongated channel 154 d of upper housing 154.

With continued reference to FIGS. 1-10 , inner shaft assembly 150 ofshaft assembly 140 supports a fire lock assembly 160 that is configuredto prevent surgical stapling apparatus 10 from firing when end effector110 is not in the articulated position, for example, about 90 degreesrelative to shaft assembly 140 and/or longitudinal axis “X1-X1”. Firelock assembly 160 includes a housing insert 162, a spring 164, and afire lock 166. Housing insert 162 is configured to be received withininsert recess 154 b and includes a base 162 a and a finger 162 b thatextends distally from base 162 a. Spring 164 of fire lock assembly 160,which may be a compression spring, is receivable within cutout 152 b oflower housing 152 of inner shaft assembly 150 and is configured toengage fire lock 166 of fire lock assembly 160. Fire lock 166 includes avertical arm 166 a and a lateral arm 166 b that extends in a laterallytransverse direction from an upper portion of vertical arm 166 a. Firelock 166 further includes a first branch 166 c that extends proximallyfrom a lower portion of vertical arm 166 a and a second branch 166 dthat extends proximally from lateral arm 166 b. First branch 166 c isconfigured to be received within cutout 152 b of inner shaft assembly150 and spring 164 of fire lock assembly 160 to enable spring 164 tourge fire lock 166 distally. Vertical arm 166 a of fire lock 166 extendsthrough elongated channel 154 d of upper housing 154 so that lateral arm166 b of fire lock 166 extends across finger 162 b of housing insert 162of fire lock assembly 160 and second branch 166 d of fire lock 166 seatsin lock recess 154 c of inner shaft assembly 150.

In operation, as illustrated in FIGS. 11-23 , I-beam assembly 156 ofshaft assembly 140 is initially in a proximal position so that anvil andcartridge assemblies 120, 130 of end effector 110 are in the unclampedposition (e.g., spaced or unapproximated) and fire lock assembly 160 isin a locked position. In the locked position, second branch 166 d offire lock 166 is supported in lock recess 154 c of upper housing 154 andsloped at an angle so that lip 156 d of knife bars 156 a is coplanarwith a proximal surface 166 e (FIG. 12 ) of second branch 166 d of firelock 166. When anvil and cartridge assemblies 120, 130 are in theunclamped position, proximal surface 166 e of second branch 166 d isspaced a distance “d” from lip 156 d of knife bars 156 a to enableI-beam assembly 160 to distally translate the distance “d,” as indicatedby arrows “C” (FIG. 14 ) for clamping anvil and cartridge assemblies120, 130 together. As I-beam assembly 160 translates distally, I-beam156 c of I-beam assembly 156 approximates anvil and cartridge assemblies120, 130 into the clamped position (see FIGS. 13 and 14 ) of endeffector 110, as indicated by arrows “B” (FIGS. 1 and 14 ). For a moredetailed description of how I-beam 156 c approximates anvil andcartridge assemblies 120, 130, reference can be made to the '033 patentincorporated herein by reference. When end effector 110 is in theclamped position, lip 156 d of I-beam assembly 156 is engaged withproximal surface 166 e of second branch 166 d of fire lock 166 so thatfire lock 166 prevents further distal advancement of I-beam assembly 156(see FIG. 15) and firing of surgical stapling apparatus 10. In theclamped position, loading unit 100 can be advanced through a surgicalaccess portal 200 (FIG. 13 ) for access to a surgical site within apatient. For a more detailed description of an example surgical accessportal, reference can be made to U.S. Pat. No. 9,788,857 to Bettuchi etal., the entire contents of which are incorporated by reference herein.Once end effector 110 is advanced through surgical access portal 200,I-beam assembly 156 of shaft assembly 140 can be drawn proximally tounclamp end effector 110 for subsequent re-clamping of end effector 110about tissue to be stapled by end effector 110.

To articulate end effector 110 of loading unit 100 to the articulatedposition (e.g., about 90 degrees), articulation rod 158 of inner shaftassembly 150 is drawn proximally (upon rotation of knob 14 a of adapterassembly 14; see FIG. 2 ), as indicated by arrow “D” (FIGS. 16-17 ). Asarticulation rod 158 translates proximally relative to fire lock 166 offire lock assembly 160, vertical arm 166 a of fire lock 166 translatesthrough elongated slot 158 a of articulation rod 158 so that an abutmentedge 158 b (FIG. 18 ) disposed at a distal end portion of elongated slot158 a of articulation rod 158 can engage a distal surface of verticalarm 166 a of fire lock 166. Continued proximal translation ofarticulation rod 158 causes fire lock 166 to compress spring 164 of firelock assembly 160 and pivot to an unlocked position (FIG. 18 ), asindicated by arrows “E.” In the unlocked position of fire lock 166, endeffector 110 is disposed in the articulated position and second branch166 d of fire lock 166 is positioned above lip 156 d of I-beam assembly156 so that lip 156 d of I-beam assembly 156 can translate beneathsecond branch 166 d of fire lock 166 for firing end effector 110 (FIG.19 ) upon actuation of I-beam assembly 156.

As seen in FIGS. 20-23 , loading unit 100 further includes a pivot guide170 having a distal end portion 172 pivotally coupled to a proximal endportion of end effector 110 by a pin 180, and a proximal end portion 174that is free and slidably received within outer tube 142 of shaftassembly 140. Pivot guide 170 further includes an arcuate inner surface176 and a curved outer surface 178. When end effector 110 is in thearticulated position (FIG. 22 ), curved outer surface 178 of pivot guide170 is engaged with an inner surface of outer tube 142 so that outertube 142 maintains arcuate inner surface 176 of pivot guide 170 inposition to guide I-beam assembly 156 along a curved path “CP” into endeffector 110. The curved path “CP” extends along arcuate inner surface176 of pivot guide 170 and an arcuate inner surface 158 y of a distalportion of articulation rod 158. In particular, when end effector 110 isin the articulated position, arcuate inner surface 176 of pivot guide170 and arcuate inner surface 158 y of articulation rod 158 define apredetermined radius “r”, for example, a perfect radius, to enableI-beam assembly 156 to curve smoothly into a knife channel 110 y of endeffector 110 (e.g., without buckling) as knife bars 156 a of I-beamassembly 156 conform, for instance bend, to the predetermined radius “r”as I-beam assembly 156 is distally advanced for firing end effector 110.

With reference to FIG. 23 , when end effector 110 is in theunarticulated position, outer tube 142 constrains a proximal portion ofpivot guide 170 inwardly such that an inner edge 176 a of arcuate innersurface 176 and an inner edge 158 z of arcuate inner surface 158 y ofarticulation rod 158 apply opposing inward forces against outer surfacesof knife bars 156 a of I-beam assembly 156 to frictionally restrainaxial movement of I-beam assembly 156.

Securement of any of the components of the presently disclosed devicesmay be effectuated using known securement techniques such welding,crimping, gluing, fastening, etc.

The various embodiments disclosed herein may also be configured to workwith robotic surgical systems and what is commonly referred to as“Telesurgery.” Such systems employ various robotic elements to assistthe clinician and allow remote operation (or partial remote operation)of surgical instrumentation. Various robotic arms, gears, cams, pulleys,electric and mechanical motors, etc. may be employed for this purposeand may be designed with a robotic surgical system to assist theclinician during the course of an operation or treatment. Such roboticsystems may include remotely steerable systems, automatically flexiblesurgical systems, remotely flexible surgical systems, remotelyarticulating surgical systems, wireless surgical systems, modular orselectively configurable remotely operated surgical systems, etc.

The robotic surgical systems may be employed with one or more consolesthat are next to the operating theater or located in a remote location.In this instance, one team of clinicians may prep the patient forsurgery and configure the robotic surgical system with one or more ofthe instruments disclosed herein while another clinician (or group ofclinicians) remotely controls the instruments via the robotic surgicalsystem. As can be appreciated, a highly skilled clinician may performmultiple operations in multiple locations without leaving his/her remoteconsole which can be both economically advantageous and a benefit to thepatient or a series of patients. For a detailed description of exemplarymedical work stations and/or components thereof, reference may be madeto U.S. Patent Application Publication No. 2012/0116416, and PCTApplication Publication No. WO2016/025132, the entire contents of eachof which are incorporated by reference herein.

Persons skilled in the art will understand that the structures andmethods specifically described herein and shown in the accompanyingfigures are non-limiting exemplary embodiments, and that thedescription, disclosure, and figures should be construed merely asexemplary of particular embodiments. It is to be understood, therefore,that the present disclosure is not limited to the precise embodimentsdescribed, and that various other changes and modifications may beeffected by one skilled in the art without departing from the scope orspirit of the disclosure. Additionally, the elements and features shownor described in connection with certain embodiments may be combined withthe elements and features of certain other embodiments without departingfrom the scope of the present disclosure, and that such modificationsand variations are also included within the scope of the presentdisclosure. Accordingly, the subject matter of the present disclosure isnot limited by what has been particularly shown and described.

What is claimed:
 1. A loading unit for a surgical apparatus comprising:a shaft assembly; an end effector extending from the shaft assembly; anarticulation rod positioned to articulate the end effector relative tothe shaft assembly between an unarticulated position and an articulatedposition; a pivot guide that has a distal end portion pivotally coupledto a proximal end portion of the end effector and having an arcuateinner surface and a curved outer surface, the curved outer surfacemaintaining the pivot guide in position to guide a beam assembly along apredetermined path when the end effector is in the articulated position;and a fire lock assembly movable in response to movement of thearticulation rod, the fire lock assembly including a spring and a firelock, the spring configured to urge the fire lock toward a firstposition to selectively prevent the beam assembly from advancing throughthe end effector for preventing the end effector from firing.
 2. Theloading unit of claim 1, wherein the beam assembly includes at least oneknife bar, the knife bar supporting an I-beam configured to advancethrough the end effector.
 3. The loading unit of claim 2, wherein thefire lock is positioned to engage the at least one knife bar to preventthe I-beam from firing the end effector.
 4. The loading unit of claim 3,wherein in the first position, the I-beam is prevented from advancingthrough the end effector.
 5. The loading unit of claim 4, wherein thearticulation rod is positioned to move the fire lock to a secondposition as the end effector moves from the unarticulated position tothe articulated position.
 6. The loading unit of claim 1, wherein theend effector includes an anvil assembly and a cartridge assembly thatare pivotally coupled together and movable between an unclamped positionand a clamped position.
 7. The loading unit of claim 6, wherein the beamassembly is configured to position the anvil and cartridge assemblies inthe clamped position as the beam assembly advances through the anvil andcartridge assemblies.
 8. The loading unit of claim 1, wherein the pivotguide is positioned to curve the beam assembly into the end effector. 9.The loading unit of claim 1, wherein the fire lock assembly ispositioned in the articulation rod.
 10. A surgical stapling apparatuscomprising: a shaft assembly; a beam assembly; an end effector extendingfrom the shaft assembly and positioned to receive the beam assembly, theend effector having a proximal end portion and a distal end portion; anarticulation rod positioned to articulate the end effector relative tothe shaft assembly between an unarticulated position and an articulatedposition; and a fire lock assembly including a fire lock received withinthe articulation rod and positioned to selectively prevent the beamassembly from advancing distally beyond the proximal end portion of theend effector for preventing the end effector from firing when the endeffector is disposed in the unarticulated position.
 11. The surgicalstapling apparatus of claim 10, wherein the end effector includes ananvil assembly and a cartridge assembly that are movable between anunclamped position and a clamped position.
 12. The surgical staplingapparatus of claim 11, wherein the beam assembly includes a knife barthat is selectively movable through the end effector.
 13. The surgicalstapling apparatus of claim 12, wherein the knife bar supports an I-beamon a distal end thereof, the I-beam positioned to advance into theproximal end portion of the end effector to move the anvil and cartridgeassemblies from the unclamped position to the clamped position.
 14. Thesurgical stapling apparatus of claim 12, wherein the fire lock isselectively engageable with the knife bar.
 15. The surgical staplingapparatus of claim 14, wherein the articulation rod is positioned toengage the fire lock to pivot the fire lock relative to the knife bar.16. The surgical stapling apparatus of claim 10, wherein the fire lockis positioned to slide along the articulation rod as the articulationrod moves the end effector relative to the shaft assembly.
 17. Thesurgical stapling apparatus of claim 10, wherein the end effector isarticulated approximately 90 degrees relative to a longitudinal axisdefined through the shaft assembly when in the articulated position. 18.The surgical stapling apparatus of claim 12, further comprising a pivotguide pivotally coupled to the end effector, the pivot guide positionedto cause the knife bar to bend around the pivot guide when the endeffector is disposed in the articulated position and positioned to limitaxial movement of the knife bar when the end effector is disposed in theunarticulated position.
 19. The surgical stapling apparatus of claim 18,wherein the pivot guide has a distal end portion pivotally coupled to aproximal end portion of the end effector by a pin, and wherein the pivotguide includes a proximal end portion that is free and slidably receivedwithin an outer tube of the shaft assembly.